Air-to-water Heat Pump
17
NOTE:
When vacuuming is finished, pressure inside the unit should be kept lower than 80Pa for at least 30
minutes to make sure there is no leak. Either charging valve 1 or charging valve 2 can be used for
vacuuming.
Charging: when vacuuming is finished and it is certain that there is no leak, charging can be done.
Leak Detection Methods:
(1) The following leak detection methods are deemed acceptable for systems containing
flammable refrigerants.
(2) Electronic leak detector shall be used to detect flammable refrigerant, but the sensitivity may
not be adequate, or may need re-calibration (Detection equipment shall be calibrated in a
refrigerant-free area).
(3) Ensure that the detector is not a potential source of ignition and is suitable for the refrigerant
used.
(4) Leak detection equipment shall be set at a percentage of the LFL of the refrigerant and shall be
calibrated to the refrigerant employed and the appropriate percentage of gas (25% maximum)
is confirmed.
(5) Leak detection fluids are suitable for us with most refrigerant but the use of detergents
containing chlorine shall be avoided as the chlorine may react with the refrigerant and corrode
the copper pipe-work.
(6) If a leak is suspected, all naked flames shall be removed / extinguished. If a leakage of
refrigerant is found which requires brazing, all of the refrigerant shall be recovered from the
system, or isolated (by means of shut off valves) in a part of the system remote from the leak.
Oxygen free nitrogen (OFN) shall then be purged through the system both before and during
the brazing process.
NOTE:
Before and during operation, use an appropriate refrigerant leak detector to monitor the operation area
and make sure the technicians can be well aware of any potential or actual leakage of inflammable gas.
Make sure the leak detecting device is applicable to inflammable refrigerant. For example, it should be
free of sparks, completely sealed and safe in nature.
10 Installation of Insulated Water Tank
10.1 Selection of Water Pipe
Inlet and outlet water pipe diameter of the unit shall be determined by the rated flow of the unit and
the recommended flow speed velocity. Flow speed of hot water pipeline shall refer to the following table.
Nominal diameter(mm)
15~20
25~40
≥50
Flow velocity(m/s)
≤0.8
≤1.0
≤1.2
